yeah they are similar to Mad Max storm.

https://youtu.be/eTwnUQwaBOM?t=40s

Whoa, that's pretty intense

As far as I can tell (just by looking at the gameplay), the wetness of the ground is actually generated by adjusting the specularity of the ground textures, which would make implementing such a feature (no wet ground/floors inside buildings) quite complicated. It'd be quite easy to disable water pools from beneath roofs with a form of raycasting ASWELL as it would be quite easy to disable the texture-based wetness from floors in prefab buildings...The real problem lies with custom made buildings built out of seperate parts. I guess one way to implement no-wetness-on-floor-textures-in-a-roofed-building in custom houses, would be to have the floor tiles raycast upwards in vector3 space and look for collisions from objects tagged as "roof" or such. If the collision was found, the specularity adjustment on the floor piece, would be disabled, keeping them dry. If no such collision was found, they would get wet just like everything else.

This kind of unorthodox system would have alot of pig holes though, for an example : In a case where a player built only a partial roof. Seeing as, if the wetness is texture based then the specularity is applied to the texture per tile. Having only a partial roof would leave you with a laser sharp edge seperating the wet and the dry floor areas in such a case. There are a few workarounds for this but none of them (that I can think of) would leave you with a flawless system and each one of them would be a waste of memory usage in my opinion.

Blood btw is a different story since it's most likely applied as a decal, so is the case with water pools, bullet holes, etc etc. Just decals with normal and specular maps on them, alpha channel cutout etc.

Really? This is your big issue? Not the supply lines, clipping, crashing, or the fact that enemies spawn inside unprotected areas of settlements? You do know these roofs are full of holes and hardly waterproof, right?

I noticed the rain effect outside, but I can't say I paid enough attention while I was inside. I'm really not there much. Too busy trying to map the Commonwealth. Next time I'm home, I'll try seeing this "issue".

why i still get rad even in the house? when the radiation storm come.
any ways to prevent it?

For a hellish storm I haven't found anything better than the https://youtu.be/xPXVj07o3C8 so far. They put you right in the thick of it.

It's not like they can't do pooled water. For example, in the Fort Hagen Command, there's a shower that's dripping water, and only a portion of the floor is wet, pooling from the drip to where the drain is.

I'm enjoying the rain. I love the raindrops on the screen when wearing power armor.

This^ There's few points in the game where I'd disagree with the wet texture because there's so few legitimately dry shelters.